Polymeric nanofibers can be used for a broad spectrum of biological and medical applications. They are of particular interest in regenerative medicine and tissue engineering because they can be potentially tailored to mimic the natural extracellular matrix (ECM) in terms of structure, chemical composition, and mechanical properties. In this context, they serve as scaffolds to direct cellular behavior and function until host cells can repopulate and resynthesize a new natural matrix. The ECM molecular network surrounding the cells provides mechanical support and regulates cellular activities. The natural ECM in human tissue is mainly composed of proteoglycans (glycosaminoglycan (GAG)) and fibrous proteins, both with nanoscale structural dimensions. Studies have shown that scaffolds with nanoscale structures support cell adhesion and proliferation, and function better than their microscale counterparts.
A number of synthetic polymer nanofibers with fiber diameters from a few tens to a few hundreds of nanometers have been fabricated for tissue engineering; these include polyglycolide (PGA), poly(L-lactic acid) (PLA), and their copolymers poly(glycolide-co-lactide) (PLGA) and poly(ε-caprolactone) (PCL). The studies demonstrated favorable biological responses of seeded cells, such as enhanced cell attachment and in vitro proliferation. Recently, there has been growing interest in the synthesis of natural polymer-based nanofibers because of their proven biocompatibility and their resorbable biodegradation products. Advantageous attributes of natural polymers include hydrophilicity, non-toxicity, less-immune reaction, as well as enhanced cell adhesion and proliferation. Collagen, gelatin, hyaluronan, chitosan, and alginate are the most commonly used natural polymers in tissue engineering. In a few recent studies, collagen and chitosan have been successfully fabricated into nanofibers and have demonstrated good cellular compatibility. The ability to generate nanofibrous matrices from natural polymers, especially those derived from plants, may provide virtually unlimited resources for the development of tissue-compatible scaffolds for functional restoration of damaged or dysfunctional tissues. This restoration currently relies mainly on the autograft and allograft procedures—surgical procedures facing the challenges of limited resources, risk of infection, and viral transmission.